Coated sodium percarbonate particles

ABSTRACT

Sodium percarbonate particles with a coating layer which comprises from 70 to 99.8% by weight of anhydrous sodium sulfate and from 0.2 to 20% by weight of a sodium borate, and whose proportion by weight is from 1 to 10% based on the mass of the sodium percarbonate particle, exhibit a high storage stability in detergent and cleaning composition formulations through a synergistic effect of sodium sulfate and sodium borate on the storage stability, and at the same time only have a small content of boron.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is US national stage of internationalapplication PCT/EP2007/056404, which had an international filing date ofJun. 27, 2007, and which was published in German under PCT Article 21(2)on Jan. 31, 2008. The international application claims priority toEuropean application EP 06117988.3, filed on Jul. 27, 2006. These priorapplications are hereby incorporated by reference in their entirety.

The invention provides coated sodium percarbonate particles with highstorage stability in detergents and cleaning compositions.

Sodium percarbonate is increasingly being used as a bleachingconstituent in detergents and cleaning compositions. For thisapplication, sodium percarbonate must have sufficient storage stabilityin detergent and cleaning composition formulations, since there isotherwise undesired loss of active oxygen and hence of bleaching actionin the course of storage of the detergents and cleaning compositions.Sodium percarbonate is moisture-sensitive and decomposes in detergentand cleaning composition formulations under the action of moisture withloss of active oxygen. To produce detergents or cleaning compositions,sodium percarbonate is therefore typically used in coated form, thecoating layers preventing the action of moisture on the coated sodiumpercarbonate particles. Suitable coating layer of inorganichydrate-forming salts, for example sodium carbonate, sodium sulfate ormagnesium sulfate and mixtures of such salts, are known, for example,from DE 24 17 572, EP-A 0 863 842 and U.S. Pat. No. 4,325,933.

U.S. Pat. No. 4,526,698 discloses sodium percarbonate particles whichare coated with a borate-containing coating layer. The coating layermay, as well as the borate, comprise further organic or inorganiccompounds. Examples of inorganic compounds mentioned are sodiumcarbonate, Glauber's salt and magnesium sulfate. It is evident from theworking examples that, for the combination of sodium borate withpolyethylene glycol, organic complexing agents, sodium silicates ormagnesium compounds, a synergistic effect occurs in the stabilization,while no synergy was observed with sodium carbonate.

WO 95/15292 discloses a process for producing alkali metal percarbonateparticles with a boric acid-containing coating layer by spraying on anaqueous solution which, in addition to boric acid, also comprises aneutral alkali metal or ammonium salt which increases the solubility ofboric acid. Preferred salts mentioned include sodium chloride, potassiumchloride, sodium sulfate and potassium sulfate. It is also mentionedthat, in addition to boric acid or instead of boric acid, it is alsopossible to use alkali metal borates. The combination of a neutralalkali metal salt with a borate is intended to bring about reducedagglomeration of the alkali metal percarbonate particles. WO 98/15292does not contain any disclosure as to the stability of alkali metalpercarbonate particles with a borate-containing coating layer.

EP 567 140 discloses a process for producing coated sodium percarbonateparticles by applying a first coating component selected from boricacids, borates and alkali metal silicates, and a second coatingcomponent selected from carbonates, hydrogencarbonates and sulfates, inwhich at least one of the coating components is applied in the form ofan aqueous suspension. Working examples 2, 4 and 5 disclose sodiumpercarbonate particles with coating layers composed of 5.5% by weight ofsodium metaborate tetrahydrate in combination with 5% by weight of soda,sodium hydrogencarbonate or sodium sulfate. It is evident from workingexamples 30 to 32 that the sodium percarbonate particles coated with acombination of borate and sodium sulfate exhibited a lower storagestability in a detergent than the sodium percarbonate particles coatedwith a combination of borate and soda, or borate and sodiumhydrogencarbonate.

DE 27 12 139 discloses sodium percarbonate particles with a coatingcomposed of dewatered sodium perborate and a sodium silicate whichadditionally comprises water-binding inert substances. Suitablewater-binding inert substances mentioned are sodium tripolyphosphate,calcined soda, sodium sulfate and sodium percarbonate. The sodiumpercarbonate particles described contain sodium perborate monohydrate inamounts of 5% by weight and more and accordingly have high contents ofboron.

The sodium percarbonate particles which have a borate-containing coatinglayer and are known from the prior art have the disadvantage that thecoating layer contains a relatively large amount of boron and, as aresult, in the case of use of the sodium percarbonate particlesdetergents or cleaning compositions, an undesirably high amount ofborate gets into the wastewater obtained in the course of use.

It has now been found that, surprisingly, in the case of sodiumpercarbonate particles comprising from 1 to 10% by weight of a coatinglayer which comprises 70% by weight or more of sodium sulfate and up to20% by weight of a sodium borate, a synergistic effect of sodium sulfateand sodium borate on the stabilization of the sodium percarbonateparticles in detergent and cleaning composition formulations occurs,i.e. such a coating layer brings about better stabilization than isachieved with a coating layer composed of sodium sulfate or sodiumborate alone.

The invention therefore provides sodium percarbonate particles with acoating layer which comprises 70 to 99.8% by weight of anhydrous sodiumsulfate and from 0.2 to 20% by weight of a sodium borate, and theproportion by weight of the coating layer is from 1 to 10% based on themass of the sodium percarbonate particle.

The inventive sodium percarbonate particles comprise a core whichconsists essentially of sodium carbonate perhydrate of composition 2Na₂CO₃.3H₂O₂. They may additionally also comprise small amounts of knownstabilizers for peroxygen compounds, for example magnesium salts,silicates, phosphates and/or chelate complexing agents. The proportionof sodium percarbonate in the core of the inventive sodium percarbonateparticles is preferably more than 80% by weight and more preferably morethan 95% by weight. The proportion of organic carbon compounds in thecore is preferably less than 1% by weight, more preferably less than0.1% by weight.

In a preferred embodiment, the core comprises small amounts of additiveswhich have a stabilizing effect on the active oxygen content, in whichcase the proportion of stabilizing additives in the core is preferablyless than 2% by weight. The stability-increasing additives used arepreferably magnesium salts, waterglass, stannates, pyrophosphates,polyphosphates, and chelate complexing agents from the group of thehydroxycarboxylic acids, aminocarboxylic acids, aminophosphonic acids,phosphonocarboxylic and hydroxyphosphonic acids, and the alkali metal,ammonium or magnesium salts thereof. In a particularly preferredembodiment, the core comprises, as a stabilizing additive, an alkalimetal silicate, preferably waterglass with an SiO₂/Na₂O modulus in therange from 1 to 3, in an amount of from 0.1 to 1% by weight. In the mostpreferred embodiment, the core, in addition to this amount of alkalimetal silicate, also comprises a magnesium compound in an amount of from50 to 2000 ppm of Mg²⁺.

The core of the inventive sodium percarbonate particles can be obtainedby one of the known preparation processes for sodium percarbonate. Asuitable preparation process for sodium percarbonate is thecrystallization of sodium percarbonate from aqueous solutions ofhydrogen peroxide and sodium carbonate, the crystallization beingperformable either in the presence or in the absence of a saltprecipitant, for which reference is made by way of example to EP-A 0 703190 and DE 2 744 574. Sodium percarbonate particles prepared by thecrystallization process in the presence of a salt precipitant may stillcomprise small amounts of the salt precipitant used, for example sodiumchloride. Likewise suitable is fluidized bed buildup granulation byspraying of aqueous hydrogen peroxide solution and aqueous soda solutiononto sodium percarbonate seeds in a fluidized bed with simultaneousevaporation of water; reference is made by way of example to WO95/06615. In addition, the reaction of solid sodium carbonate with anaqueous hydrogen peroxide solution and subsequent drying is anothersuitable preparation process.

In a preferred embodiment, the inventive sodium percarbonate particleshave a core of sodium percarbonate which is obtainable by fluidized bedgranulation from aqueous solutions of hydrogen peroxide and sodiumcarbonate. Such a fluidized bed granulation affords a core materialwhich differs from the core materials obtained by other preparationprocesses by a particularly dense, shell-like structure and a smoothersurface. Inventive coated sodium percarbonate particles whose core hasbeen produced by fluidized bed buildup granulation exhibit an improvedstorage stability in detergent and cleaning composition formulationscompared to particles whose core has been produced by another process.

The inventive coated sodium percarbonate particles comprise, in additionto the core composed of sodium percarbonate, also a coating layer whichcomprises 70 to 99.8% by weight of anhydrous sodium sulfate and from 0.2to 20% by weight of a sodium borate, and the proportion by weight of thecoating layer is from 1 to 10% based on the mass of the sodiumpercarbonate particle. The coating layer preferably comprises at least80% by weight, more preferably at least 90% by weight, of sodiumsulfate. The proportion of sodium borate in the coating layer ispreferably 0.2 to less than 10% by weight, more preferably 0.5 to 5% byweight. The amounts stated for sodium borate are based on a calculationas anhydrous sodium metaborate NaBO₂. The sodium borate may, however,also be present in the coating layer in other compositions, for examplein the form of sodium tetraborate Na₂B₄O₇, sodium octaborate Na₂B₈O₁₃ orsodium pentaborate Na₂B₁₀O₁₆.

The proportion by weight of the coating layer based on the mass of thesodium percarbonate particle is preferably from 2 to 8%, more preferablyfrom 2 to 6%. In a particularly preferred embodiment, the proportion ofsodium borate in the coating layer and the amount of the coating layerare selected such that the content of boron in the inventive coatedsodium percarbonate particles is in the range from 20 to 700 ppm ofboron, especially from 50 to 350 ppm of boron.

The inventive coated sodium percarbonate particles may additionallycomprise up to 25% by weight of sodium carbonate, sodiumhydrogencarbonate or mixtures thereof in the coating layer whichcomprises sodium sulfate and a sodium borate. Sodium carbonate andsodium hydrogencarbonate may also be present in the form of mixed saltswith sodium sulfate, and sodium carbonate preferably in the form of amixed salt of the composition 2 Na₂SO₄.Na₂CO₃. The coating layer whichcomprises sodium sulfate and a sodium borate preferably comprises, inaddition to sodium sulfate, sodium borate, sodium carbonate, sodiumhydrogencarbonate and mixed salts thereof, not more than 5% by weight offurther compounds.

In addition to the inventive coating layer which comprises sodiumsulfate and a sodium borate, the inventive sodium percarbonate particlesmay also comprise one or more further coating layers, which may bedisposed either between the core and the inventive coating layer oroutside the inventive coating layer. The inventive coating layer ispreferably present immediately on the core material of sodiumpercarbonate.

Between the coating layers and between the innermost coating layer andthe core, there may exist a sharp boundary at which the compositionchanges abruptly. In general, however, there will be a transition zonein each case between the individual coating layers and between theinnermost coating layer and the core, said transition zone comprisingthe components of both adjacent layers. Such transition zones form, forexample, as a result of the application of a coating layer in the formof an aqueous solution, a portion of the layer below being partlydissolved at the start of the layer buildup, so as to form a transitionzone which comprises the constituents of both layers. In the preferredembodiment, in which the inventive coating layer is present immediatelyon the core material of sodium percarbonate, a transition layer whichcomprises sodium sulfate, sodium borate, sodium carbonate, sodiumhydrogencarbonate, and also mixed salts of these components, may thusform between the core and the inventive coating layer.

The inventive coating layer which comprises sodium sulfate and a sodiumborate is preferably configured such that it covers the material belowit to an extent of more than 95%, preferably to an extent of more than98% and especially completely.

In a preferred embodiment, the inventive sodium percarbonate particleshave a coating layer which is produced by spraying an aqueous solutionwhich comprises sodium sulfate and a sodium borate in dissolved form,and evaporating water in a fluidized bed. The coated sodium percarbonateparticles thus obtainable differ from sodium percarbonate particles inwhich one of the components of the coating layer is applied in solidform by a homogeneous distribution of sodium sulfate and sodium boratein the coating layer and have a better storage stability in detergentand cleaning composition formulations compared with sodium percarbonateparticles with inhomogeneous distribution of sodium sulfate and sodiumborate in the coating layer.

In a particularly preferred embodiment, the inventive sodiumpercarbonate particles have a coating layer which is obtained by sprayapplication of an aqueous solution which comprises dissolved sodiumsulfate and a sodium borate and comprises a total of not more than 25%by weight of dissolved salts. While the prior art teaches use of highlyconcentrated solutions of the coating components to apply a coatinglayer, in order to minimize the amount of water to be evaporated, it hasnow been found that, surprisingly, sodium percarbonate particles with aninventive coating layer which comprises sodium sulfate and a sodiumborate and which is obtainable by spray application of an aqueoussolution comprising not more than 25% by weight of dissolved salts havea better storage stability in detergent and cleaning compositionformulations than sodium percarbonate particles which are obtainable byspray application of an aqueous solution with a higher content ofdissolved salts.

Solutions which are obtained by dissolving sodium sulfate and an alkalimetal borate in water can be used to apply the inventive coating layerwhich comprises sodium sulfate and a sodium borate. If the alkali metalborate contains a different alkali metal than sodium, the sodium borateof the coating layer forms in the course of spraying of the solutionwith sodium ions which originate from the sodium sulfate.

During the spray application of the aqueous solution which comprisesdissolved sodium sulfate and a sodium borate, the majority of the waterpresent therein, especially more than 90% of the water present in theaqueous solution, is preferably already evaporated as a result of supplyof heat, such that only a small portion of the material below it ispartly dissolved again during the spray application of the coating layerand a solid coating layer forms already during the spray application.The inventive coating layer is applied preferably by spraying an aqueoussolution comprising sodium sulfate and a sodium borate in a fluidizedbed and more preferably by the process described in EP-A 0 970 917, withwhich it is possible to achieve a dense coating layer even with smallamounts of coating layer material. The coating layer is applied in afluidized bed preferably with supply of a drying gas to the fluidizedbed, such that a temperature in the range from 30 to 90° C., preferablyfrom 50 to 70° C., is established in the fluidized bed.

The inventive coated sodium percarbonate particles having a coatinglayer which comprises sodium sulfate and a sodium borate surprisinglyexhibit a better storage stability in detergent and cleaning compositionformulations than uncoated sodium percarbonate particles which have onlyone of the two components in the coating layer. Their storage stabilityis also improved over sodium percarbonate particles which, instead ofsodium sulfate, comprise in the coating layer another water-bindingsalt, for example sodium carbonate or sodium hydrogencarbonate, in thesame amount in combination with a sodium borate. The improved storagestability in detergent and cleaning composition formulations leads tolower losses of active oxygen content during the storage of thedetergent and cleaning composition formulations in a moist environment.

The sodium percarbonate particles coated in accordance with theinvention also exhibit no caking under the action of pressure and only asmall release of heat in substance and can therefore be stored safely ina silo, without there being any caking in the silo or any self-heatingof the silo contents.

Furthermore, detergent and cleaning composition formulations whichcomprise sodium percarbonate particles coated in accordance with theinvention have improved safety when being stored in silo vessels, sincethey exhibit only slight self-heating, if any, in the case of adiabaticwarm storage.

In a further embodiment of the invention, the coated sodium percarbonateparticles may have an additional coating layer which, as the mainconstituent, comprises an alkali metal silicate having an SiO₂ to alkalimetal oxide modulus of more than 2.5. The additional coating layer ispreferably present on top of the inventive coating layer. The additionalcoating layer comprises an alkali metal silicate as the main constituentwhen it does not comprise any further component in a proportion byweight greater than the proportion of alkali metal silicate. The modulusof the alkali metal silicate is preferably in the range from 3 to 5 andmore preferably in the range from 3.2 to 4.2. The proportion of theadditional coating layer in the inventive coated sodium percarbonateparticles is preferably in the range from 0.2 to 3% by weight. Theproportion of alkali metal silicate in the material of the additionalcoating layer is preferably more than 50% by weight and more preferablymore than 80% by weight. The alkali metal silicate used in theadditional coating layer is preferably sodium silicate and morepreferably sodium waterglass.

Sodium percarbonate particles which have been coated in accordance withthe invention and have an additional coating layer which comprises, asthe main constituent, an alkali metal silicate having an SiO₂ to alkalimetal oxide modulus of more than 2.5 additionally exhibit a retardeddissolution time in water and an improved storage stability in aqueousliquid or gel-form media at water contents of up to 15% by weight. Theycan therefore be used advantageously to produce liquid or gel-formdetergent or cleaning composition formulations.

In a further embodiment of the invention, the coated sodium percarbonateparticles may additionally have, on their surface, from 0.01 to 1% byweight, preferably from 0.1 to 0.5% by weight, of a fine oxide of theelements Si, Al or Ti, or of a mixed oxide of these elements. Suitablefine oxides are, for example, pyrogenic oxides which are obtained byflame hydrolysis of volatile compounds of the elements silicon, aluminumor titanium, or of mixtures of these compounds. The pyrogenic oxides ormixed oxides obtainable by this route preferably have a mean primaryparticle size of less than 50 nm and may be aggregated to largerparticles whose mean particle size is preferably less than 20 μm.Likewise suitable are precipitated oxides which have been precipitatedfrom aqueous solutions of compounds of the elements silicon, aluminum ortitanium, or mixtures of these compounds. The precipitated oxides ormixed oxides may, as well as silicon, aluminum and/or titanium, alsocomprise small amounts of alkali metal or alkaline earth metal ions. Themean particle size of the precipitated oxides is preferably less than 50μm and more preferably less than 20 μm. The specific BET surface area ofthe fine oxides is preferably in the range from 100 to 300 m²/g.

The coated sodium percarbonate particles preferably have, on theirsurface, a hydrophobized fine oxide and more preferably a hydrophobizedfumed or precipitated silica. Hydrophobized oxides in the context of theinvention are oxides which have, on their surface, organic radicalsbonded via chemical bonds and are not wetted by water. Hydrophobizedoxides can be prepared, for example, by reacting pyrogenic orprecipitated oxides with organosilanes, silazanes or polysiloxanes.Suitable silicon compounds for preparing hydrophobized oxides are knownfrom EP-A 0 722 992, page 3 line 9 to page 6 line 6. Particularpreference is given to hydrophobized oxides which have been prepared byreacting a fine oxide with a silicon compound of compound classes (a) to(e) and (k) to (m) listed in EP-A 0 722 992. The hydrophobized fineoxides preferably have a methanol wettability of at least 40.

Sodium percarbonate particles which have been coated in accordance withthe invention and additionally have, on their surface, a fine oxideexhibit an even lower tendency to cake in the course of storage, inparticular in the course of storage under pressure stress, and thereforehave even better silo storability. Furthermore, such particles indetergent and cleaning composition formulations have a further increasedstorage stability.

The inventive sodium percarbonate particles preferably have a meanparticle size in the range from 0.2 to 5 mm and more preferably in therange from 0.5 to 2 mm. Preference is given to sodium percarbonateparticles having a low fines fraction, preferably having a fraction ofless than 10% by weight of particles smaller than 0.2 mm and morepreferably less than 10% by weight of particles having a particle sizeof less than 0.3 mm.

The inventive sodium percarbonate particles preferably have anessentially spherical shape with a smooth surface. Particles with asmooth surface have a surface roughness of less than 10% of the particlediameter and preferably of less than 5% of the particle diameter.

An appropriate selection of the particle size and particle form allowsthe storage stability of the inventive sodium percarbonate particles indetergent and cleaning composition formulations to be improved further.

The inventive coated sodium percarbonate particles can advantageously beused as a bleaching constituent in detergents and cleaning compositions.Detergents in the context of the invention are all formulations whichare suitable for cleaning textiles in an aqueous wash liquor. Cleaningcompositions in the context of the invention are all formulations which,in interaction with water, are suitable for cleaning surfaces whichabsorb only a small amount of water, if any. A form of cleaningcompositions preferred in the context of the invention is that ofmachine dishwasher detergents which are suitable for machine cleaning ofdishware and cutlery.

The invention further provides detergents and cleaning compositionswhich comprise sodium percarbonate particles coated in accordance withthe invention. The inventive detergents and cleaning compositionscomprise the inventive coated sodium percarbonate particles preferablyin an amount of from 1 to 40% by weight based on the total amount ofdetergent or cleaning composition.

The inventive detergents and cleaning compositions may be in solid formand may then also comprise further components in the form of powder orin the form of granules beside the inventive coated sodium percarbonateparticles. Furthermore, they may also comprise press-shaped bodies, inwhich case the inventive coated sodium percarbonate particles may bepart of the press-shaped bodies. Such press-shaped bodies in the form ofextrudates, pellets, briquettes or tablets can be produced by processesfor pressing agglomeration, especially by extrusion, strand pressing,perforation pressing, roller compaction or tableting. For theperformance of the pressing agglomeration, the inventive detergents orcleaning compositions may additionally comprise a binder which imparts ahigher strength to the shaped bodies in the course of pressingagglomeration. However, for inventive detergents and cleaningcompositions comprising press-shaped bodies preference is given to notusing any additional binder and one of the wash-active constituents, forexample a nonionic surfactant, fulfills the function of the binder.

The inventive detergents and cleaning compositions may additionally alsobe in liquid form or gel form and comprise the inventive coated sodiumpercarbonate particles dispersed in a liquid phase, or a gel phase. Inaddition to the inventive coated sodium percarbonate particles, furtherparticles may be dispersed in the liquid phase, or the gel phase. TheTheological properties of the liquid phase, or of the gel phase arepreferably adjusted such that the particles dispersed therein remainsuspended and do not settle during storage. The composition of a liquidphase is preferably selected in such a way that it has thixotropic orpseudoplastic flow properties. To establish such flow properties,suspension auxiliaries, such as swelling clays, especiallymontmorillonites, precipitated and fumed silicas, vegetable gums,especially xanthans, and polymeric gelling agents, such as vinylpolymers containing carboxyl groups, may be added.

Inventive detergents and cleaning compositions in liquid form or gelform preferably comprise inventive coated sodium percarbonate particleswith an additional coating layer which, as the main constituent,comprises an alkali metal silicate having an SiO₂ to alkali metal oxidemodulus of more than 2.5 In this embodiment, the detergents and cleaningcompositions may comprise up to 15% by weight of water without therebeing any partial dissolution of the coated sodium percarbonateparticles and a resulting release of hydrogen peroxide into the liquidphase or gel phase during storage.

The inventive detergents and cleaning compositions may, as well as theinventive coated sodium percarbonate particles, comprise, as furthercomponents, for example, also surfactants, builders, alkalinecomponents, bleach activators, enzymes, chelating complexing agents,graying inhibitors, foam inhibitors, optical brighteners, fragrances anddyes.

Suitable surfactants for the inventive detergents and cleaningcompositions are in particular anionic, nonionic and cationicsurfactants.

Suitable anionic surfactants are, for example, surfactants withsulfonate groups, preferably alkylbenzenesulfonates, alkanesulfonates,alpha-olefinsulfonates, alpha-sulfo fatty acid esters orsulfosuccinates. In the case of alkylbenzenesulfonates, preference isgiven to those having a straight-chain or branched alkyl group havingfrom 8 to 20 carbon atoms, especially having from 10 to 16 carbon atoms.Preferred alkanesulfonates are those with straight alkyl chains havingfrom 12 to 18 carbon atoms. In the case of alpha-olefinsulfonates,preference is given to the reaction products of the sulfonation ofalpha-olefins having from 12 to 18 carbon atoms. In the case of thealpha-sulfo fatty acid esters, preference is given to sulfonationproducts of fatty acid esters formed from fatty acids having from 12 to18 carbon atoms and short-chain alcohols having from 1 to 3 carbonatoms. Suitable anionic surfactants also include surfactants having asulfate group in the molecule, preferably alkyl sulfates and ethersulfates. Preferred alkyl sulfates are those with straight-chain alkylradicals having from 12 to 18 carbon atoms. Also suitable arebeta-branched alkyl sulfates and alkyl sulfates mono- orpoly-alkyl-substituted in the middle of the longest alkyl chain.Preferred ether sulfates are the alkyl ether sulfates which are obtainedby ethoxylating linear alcohols having from 12 to 18 carbon atoms withfrom 2 to 6 ethylene oxide units and then sulfating. The anionicsurfactants used may finally also be soaps, for example alkali metalsalts of lauric acid, myristic acid, palmitic acid, stearic acid and/ornatural fatty acid mixtures, for example coconut, palm kernel or tallowfatty acids.

Suitable nonionic surfactants are, for example, alkoxylated compounds,especially ethoxylated and propoxylated compounds. Particularly suitablenonionic surfactants are condensation products of alkylphenols or fattyalcohols with from 1 to 50 mol, preferably from 1 to 10 mol, of ethyleneoxide and/or propylene oxide. Likewise suitable are polyhydroxy fattyacid amides in which an organic radical having one or more hydroxylgroups which may also be alkoxylated is bonded to the amide nitrogen.Likewise suitable as nonionic surfactants are alkylglycosides with astraight-chain or branched alkyl group having from 8 to 22 carbon atoms,especially having from 12 to 18 carbon atoms, and a mono- or diglycosideradical, which is preferably derived from glucose.

Suitable cationic surfactants are, for example, mono- and dialkoxylatedquaternary amines having a C₆- to C₁₈-alkyl radical bonded to thenitrogen and one or two hydroxyalkyl groups.

The inventive detergents and cleaning compositions further comprisebuilders which are capable of binding calcium and magnesium ionsdissolved in water in the course of use. Suitable builders are alkalimetal phosphates and alkali metal polyphosphates, especially pentasodiumtriphosphate; water-soluble and water-insoluble sodium silicates,especially sheet silicates of the formula Na₅Si₂O₅; zeolites of the A, Xand/or P structures; and trisodium citrate. In addition to the builders,it is also possible to use organic cobuilders, for example polyacrylicacid, polyaspartic acid and/or acrylic acid copolymers with methacrylicacid, acrolein or vinyl monomers containing sulfonic acid, and thealkali metal salts thereof.

The inventive detergents and cleaning compositions generally alsocomprise alkaline components which upon the intended use bring about apH in the range from 8 to 12 in the wash liquor, or the aqueous cleaningcomposition solution. Suitable alkaline components are in particularsodium carbonate, sodium sesquicarbonate, sodium metasilicate and othersoluble alkali metal silicates.

Suitable bleach activators for the inventive detergents and cleaningcompositions are in particular compounds having one or moreperhydrolyzable acyl groups bonded to nitrogen or to oxygen, which reactwith the hydrogen peroxide released from the sodium percarbonateparticles in the wash liquor, or the aqueous cleaning compositionsolution, to give peroxycarboxylic acids. Examples of such compounds arepolyacylated alkylenediamines, especially tetraacetylethylenediamine(TAED); acylated triazine derivatives, especially1,5-diacetyl-2,4-dioxohexahydro-1,3,5-triazine (DADHT); acylatedglycolurils, especially tetraacetylglycoluril (TAGU); N-acylimides,especially N-nonanoylsuccinimide (NOSI); acylated phenolsulfonates,especially n-nonanoyl- or isononanoyloxybenzenesulfonate (n- oriso-NOBS); carboxylic anhydrides such as phthalic anhydride; acylatedpolyhydric alcohols such as ethylene glycol diacetate,2,5-diacetoxy-2,5-dihydrofuran, acetylated sorbitol and mannitol, andacylated sugars such as pentaacetylglucose; enol esters; and N-acylatedlactams, especially N-acylcaprolactams and N-acylvalerolactams. Likewisesuitable as bleach activators are amino-functionalized nitrites andsalts thereof (nitrile quats), which are known, for example, from thejournal Tenside Surf. Det. 1997, 34(6), pages 404-409. The bleachactivators used may also be transition metal complexes which canactivate hydrogen peroxide for bleaching stain removal. Suitabletransition metal complexes are, for example, known from EP-A 0 544 490page 2 line 4 to page 3 line 57; WO 00/52124 page 5 line 9 to page 8line 7 and page 8 line 19 to page 11, line 14; WO 04/039932 page 2 line25 to page 10 line 21; WO 00/12808 page 6 line 29 to page 33 line 29; WO00/60043 page 6 line 9 to page 17 line 22; WO 00/27975 page 2 lines 1 to18 and page 3 line 7 to page 4 line 6; WO 01/05925 page 1 line 28 topage 3 line 14; WO 99/64156 page 2 line 25 to page 9 line 18; and GB-A 2309 976 page 3 line 1 to page 8 line 32.

The inventive detergents and cleaning compositions may further compriseenzymes which enhance the cleaning action, especially lipases,cutinases, amylases, neutral and alkaline proteases, esterases,cellulases, pectinases, lactases and/or peroxidases. The enzymes may beadsorbed on carrier substances or be embedded into coating substances inorder to protect them from decomposition.

The inventive detergents and cleaning compositions may also comprisechelating complexing agents for transition metals, with which acatalytic decomposition of active oxygen compounds in the wash liquor,or the aqueous cleaning composition solution, can be prevented. Suitableexamples are phosphonates, such as hydroxyethane-1,1-disphosphonate,nitrilotrimethylenephosphonate,diethylenetriaminepenta-(methylenephosphonate),ethylenediaminetetra(methylenephosphonate),hexamethylenediaminetetra(methylenephosphonate) and the alkali metalsalts thereof. Likewise suitable are nitrilotriacetic acid andpolyaminocarboxylic acids, especially ethylenediaminetetraacetic acid,diethylenetriaminopentaacetic acid, ethylenediamine-N,N′-disuccinicacid, methylglycinediacetic acid and polyaspartates, and the alkalimetal and ammonium salts thereof. Finally, polybasic carboxylic acidsand especially hydroxycarboxylic acids, especially tartaric acid andcitric acid, are also suitable as chelating complexing agents.

The inventive detergents may additionally comprise graying inhibitorswhich keep soil detached from the fiber suspended and preventreattachment of the soil to the fiber. Suitable graying inhibitors are,for example, cellulose ethers such as carboxymethylcellulose and thealkali metal salts thereof, methylcellulose, hydroxyethylcellulose andhydroxypropylcellulose. Polyvinylpyrrolidone is likewise suitable.

The inventive detergents and cleaning compositions may further alsocomprise foam inhibitors which reduce foam formation in the wash liquor.Suitable foam inhibitors are, for example, organopolysiloxanes such aspolydimethylsiloxane, paraffins and/or waxes, and mixtures thereof withfine silicas.

The inventive detergents may optionally comprise optical brightenerswhich attach to the fiber, absorb light in the UV range and fluoresce ina blue color in order to compensate for yellowing of the fiber. Suitableoptical brighteners are, for example, derivatives ofdiaminostilbenedisulfonic acid, such as alkali metal salts of4,4′-bis(2-anilino-4-morpholino-1,3,5-triazinyl-6-amino)stilbene-2,2′-disulfonicacid, or substituted diphenylstyryls, such as alkali metal salts of4,4′-bis(2-sulfostyryl)diphenyl.

The inventive detergents and cleaning compositions may finally alsocomprise fragrances and dyes.

Inventive detergents and cleaning compositions in liquid form or gelform may additionally also comprise up to 30% by weight of organicsolvent, for example methanol, ethanol, n-propanol, isopropanol,n-butanol, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol,1,4-butylene glycol, glycerol, diethylene glycol, ethylene glycol methylether, ethanolamine, diethanolamine and/or triethanolamine.

As compared with detergents and cleaning compositions which do notcomprise sodium percarbonate particles coated in accordance with theinvention, the inventive detergents and cleaning compositions exhibit abetter storage stability with lower losses of active oxygen content inthe course of storage under moist conditions.

One embodiment of the inventive cleaning compositions is that of machinedishwasher detergents, preferably in the form of tablets, in which casethe dishwasher detergents may also comprise a silver anticorrosivebeside the inventive coated sodium percarbonate particles. Silveranticorrosives are agents which reduce or prevent the tarnishing ofnonferrous metals, especially of silver, during machine cleaning withthe machine dishwasher detergent. Suitable silver anticorrosives arecompounds from the group of the triazoles, benzotriazoles,bisbenzotriazoles, aminotriazole and alkylaminotriazoles. The compoundsof the substance classes mentioned may also have substituents, forexample linear or branched alkyl groups having from 1 to 20 carbonatoms, as well as vinyl, hydroxyl, thiol or halogen radicals. In thecase of bisbenzotriazoles, preference is given to compounds in which thetwo benzotriazole groups are each bonded in the 6 position via an Xgroup, where X may be a bond, a straight-chain alkylene group which isoptionally substituted by one or more C₁- to C₄-alkyl groups and haspreferably from 1 to 6 carbon atoms, a cycloalkyl radical having atleast 5 carbon atoms, a carbonyl group, a sulfonyl group, an oxygen atomor a sulfur atom. A particularly preferred silver anticorrosive istolyltriazole.

EXAMPLES

Preparation of Coated Sodium Percarbonate Particles

To produce the coated sodium percarbonate particles, sodium percarbonateparticles were used which had been prepared by the process described inEP-B 0 716 640 by fluidized bed buildup granulation from aqueoushydrogen peroxide solution and aqueous sodium carbonate solution and hada mean particle diameter x₅₀ of 0.78 mm and a fines fraction of smallerthan 0.2 mm of less than 2% by weight. The coating layer was applied tothese particles by the process described in EP-B 0 863 842 in paragraph[0021] by spraying on a 20% by weight aqueous solution of the coatingsubstances in a fluidized bed at a fluidized bed temperature of from 55to 60° C. and simultaneously evaporating water and subsequently dryingat a temperature of not more than 90° C. for 30 min. The amounts ofcoating substance reported in percent by weight in table 1 are based onthe total amount of coating substances sprayed on, calculated withoutwater of crystallization, relative to the total amount of sodiumpercarbonate particles and coating substances used.

Storage Stability in Washing Powder

To determine the storage stability in washing powder, 405 g ofzeolite-containing heavy-duty powder detergent IEC-A* BASE(wfk-Testgewebe GmbH, Krefeld) were mixed with 15 g of TAED and 80 g ofsodium percarbonate in a tumbling mixer for at least 10 min. The mixturewas filled into an E2 detergent package (dimensions 19×14×4.5 cm) havinga water-repellent impregnation, which was sealed with hotmelt adhesive.The detergent package was then stored in a climate-controlled cabinet at35° C. and 80% relative air humidity. After the detergent package hadbeen cooled to room temperature outside the climate-controlled cabinet,the contents of the detergent package were divided by means of a sampledivider into samples of 12 g each. The active oxygen content before andafter storage was determined by permanganometry in a customary manner.The active oxygen content before the storage and the active oxygencontent after 8 weeks of storage were used to determine the retention ofthe active oxygen content (Oa retention) in percent as a measure of thestorage stability in washing powder.

TABLE 1 Storage stability of coated sodium percarbonate particles inwashing powder Storage stability as a function of the amount of coatingsubstance [Oa Composition of retention in percent] the coating layer 4%by weight 3% by weight 2% by weight in parts by of coating of coating ofcoating weight substances substances substances Na₂SO₄ 100* 51 48 43Na₂SO₄/NaBO₂ 59 54 37 99.5:0.5 Na₂SO₄/NaBO₂ 99:1 62 51 45 Na₂SO₄/NaBO₂71 59 46 97.5:2.5 Na₂SO₄/NaBO₂ 95:5 81 59 53 Na₂SO₄/NaBO₂ 90:10 79Na₂SO₄/NaBO₂ 80:20 76 Na₂SO₄/NaBO₂ 71 50:50* *noninventive

The tests were repeated for a coating substance composition of 95 partsby weight of sodium sulfate and 5 parts by weight of sodium metaborateor pure sodium sulfate, by spraying on 4% by weight of coatingsubstances at a constant spray rate of 11 g/min and varying theconcentration of the coating substances in the solution sprayed from 15to 30% by weight.

TABLE 2 Storage stability of coated sodium percarbonate particles inwashing powder Composition Storage stability as of the a function of thecoating concentration of the layer in solution sprayed on parts by [Oaretention in percent] weight 15% by wt. 20% by wt. 25% by wt. 30% by wt.Na₂SO₄ 100* 45 53 43 44 Na₂SO₄/ 83 79 74 63 NaBO₂ 95:5 *noninventive

The invention claimed is:
 1. Sodium percarbonate particles comprising acoating layer, wherein said coating layer comprises 80 to 95% by weightof anhydrous sodium sulphate and 5 to 20% by weight of a sodium borate,and the weight proportion of the coating layer based on the mass of thesodium percarbonate particle is from 3 to 4% and wherein thedistribution of the anhydrous sodium sulphate and the sodium borate inthe coating layer is homogeneous.
 2. The sodium percarbonate particlesof claim 1, wherein the coating layer comprises less than 10% by weightof a sodium borate.
 3. The sodium percarbonate particles of claim 1,having a content of boron in the range of 20 to 700 ppm based on themass of the sodium percarbonate particles.
 4. The sodium percarbonateparticles of claim 1, wherein the coating layer further comprises up to25% by weight of sodium carbonate, sodium hydrogencarbonate or mixturesthereof.
 5. The sodium percarbonate particles of claim 1, wherein saidcoating layer is obtained by spraying an aqueous solution of sodiumsulphate and sodium borate in dissolved form and evaporating water in afluidized bed, and wherein said aqueous solution contains not more than25% by weight of dissolved salts.
 6. The sodium percarbonate particlesof claim 5, wherein said aqueous solution is sprayed onto a sodiumpercarbonate particle which is obtained from aqueous solutions ofhydrogen peroxide and sodium carbonate by fluidized bed granulation. 7.Detergent, comprising sodium percarbonate particles according toclaim
 1. 8. The detergent of claim 7, wherein the coating layer of saidsodium percarbonate particles comprises less than 10% by weight of asodium borate.
 9. The detergent of claim 7, wherein said sodiumpercarbonate particles comprise boron in the range of 20 to 700 ppmbased on the mass of the sodium percarbonate particles.
 10. Thedetergent of claim 7, wherein the coating layer of said sodiumpercarbonate particles further comprises up to 25% by weight of sodiumcarbonate, sodium hydrogencarbonate or mixtures thereof.
 11. Thedetergent of claim 7, wherein the coating layer of said sodiumpercarbonate particles is obtained by spraying an aqueous solution ofsodium sulphate and sodium borate in dissolved form and evaporatingwater in a fluidized bed, and wherein said aqueous solution contains notmore than 25% by weight of dissolved salts.
 12. The detergent of claim7, wherein said aqueous solution is sprayed onto a sodium percarbonateparticle which is obtained from aqueous solutions of hydrogen peroxideand sodium carbonate by fluidized bed granulation.
 13. Cleaningcomposition, comprising sodium percarbonate particles according toclaim
 1. 14. The cleaning composition of claim 13, wherein the coatinglayer of said sodium percarbonate particles comprises less than 10% byweight of a sodium borate.
 15. The cleaning composition of claim 13,wherein said sodium percarbonate particles comprise boron in the rangeof 20 to 700 ppm based on the mass of the sodium percarbonate particles.16. The cleaning composition of claim 13, wherein the coating layer ofsaid sodium percarbonate particles further comprises up to 25% by weightof sodium carbonate, sodium hydrogencarbonate or mixtures thereof. 17.The cleaning composition of claim 13, wherein the coating layer on saidsodium percarbonate particles is obtained by spraying an aqueoussolution of sodium sulphate and sodium borate in dissolved form andevaporating water in a fluidized bed, and wherein said aqueous solutioncontains not more than 25% by weight of dissolved salts.
 18. The sodiumpercarbonate particles of claim 1, wherein the particles comprise a coreconsisting of essentially of sodium carbonate perhydrate of composition2Na₂CO₃.3H₂O₂ and less than 2% of stabilizers for peroxygen compoundsselected from the group consisting of: magnesium salts, silicates,phosphates and chelate complexing agents.
 19. The sodium percarbonateparticles of claim 1, wherein the particles have a mean particle size inthe range from 0.5 to 2 mm.